This application claims the priority of German patent document number 10 2007 036 527.8-13, filed Aug. 2, 2007, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a nozzle arrangement for a gas turbine engine.
During the operation of gas turbine engines, particularly in aircraft, exhaust gases which flow out through the nozzles of the engines are directed through an ejector, for the purposes of noise reduction, infrared blocking and engine compartment exhaust, for example. In the conventional design of nozzle and ejector, aerodynamic vibrations are excited when the airflows merge, resulting in high noise pollution.
To reduce noise in jet engines, the conventional procedure has been to mix the ambient airflow with the jet engine flow in order to reduce its velocity and the associated noises (U.S. Pat. No. 3,710,890). To achieve a great noise reduction, large ejector inlets with pronounced secondary airflows have been used, resulting in an unacceptable loss of thrust at cruising speeds.
In a known noise reducing nozzle for an aircraft gas turbine engine disclosed in German patent document DE 41 14 319 A1, an ejector nozzle receives the exhaust gases from an outlet of a core engine of the aircraft gas turbine engine. A gap is formed between the outlet of the engine nozzle and the inlet of the ejector nozzle, and ambient air flows in through the gap and mixes with the accelerated exhaust gases of the engine. For further noise reduction, during take-off of an aircraft, a plurality of mutually spaced, retractable channel flaps, which are arranged on the ejector nozzle, are deployed into its inner region through which the exhaust gases are directed. The channel flaps thereby reduce the cross-section of the ejector nozzle.
A disadvantage of this arrangement is that moving parts are required in order to achieve the noise reduction. Such parts are extremely susceptible to damage under the high thermal loading by the exhaust gases.
A further noise reducing nozzle and ejector arrangement is disclosed in German patent document DE 694 06 370 T2. In this arrangement, an attempt is made to achieve the noise reduction by specifically influencing the exhaust gas flow on entry into the ejector.
One object of the present invention is to provide a noise reducing ejector nozzle arrangement which prevents the excitation of aerodynamic vibrations, and thus greatly reduces the noise and vibrations.
This and other objects and advantages are achieved by the nozzle arrangement according to the invention, in which an ejector nozzle is arranged axially downstream from the engine nozzle. A gap is formed between the outlet of the engine nozzle and the inlet of the ejector nozzle, with a flange which reduces the width of the gap being arranged at the outlet of the engine nozzle.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.